Covalent modification of proteins is a common mechanism for alteration of protein function and stability. The small peptide ubiquitin is covalently linked to lysine residues on many proteins. Ubiquitination often targets proteins for degradation. The ubiquitin-proteasome system is responsible for quality control and regulatory functions in the cell.
Existing methods for the detection of ubiquitination in a cell rely on donor-acceptor methods such as fluorescence resonance energy transfer and time-resolved fluorescence. Such methods are cumbersome and subject to interference by cellular components.
What is needed are simple, robust methods for detecting covalent protein conjugations in a variety of situations.